Many Muslims consider any depiction of Mohammad deeply offensive, and the head of this Paris mosque is among them.

DALIL BOUBAKEUR, HEAD OF PARIS MOSQUE, SAYING

"We pity the authors, who thought it useful to choose, with particular cowardice - a period where relations between Islam and public order are already difficult. They are pouring oil onto the flames."

Last week a film made in the United States portraying Mohammad as a womanising buffoon led to violent protests around the world and the death of the U.S. ambassador to Libya.

Charlie Hebdo's editor says the magazine aims to poke fun at all forms of extremism.

CHARB, CHARLIE HEBDO EDITOR, SAYING

"One has the impression that everybody's driven by fear. That's what this small handful of fundamentalists that doesn't represent anyone wants to do: govern through fear."

Riot police are guarding Charlie Hebdo's offices, and security has been stepped up at France's diplomatic posts around the world.

This is the French Prime Minister.

FRENCH PRIME MINISTER JEAN-MARC AYRAULT SAYING:

"We have a free press that can express itself right up to the point of caricature. But there is also a question of responsibility. And as far as public order is concerned, all precautions will be taken to maintain order."

Charlie Hebdo has been through this before.

Its Paris offices were fire bombed last November after it published a mocking caricature of Mohammad.